Humidity control device for equipment front end module of semiconductor processing or characterization tool

Abstract

A load port receives a wafer carrier. An equipment front end module (EFEM) transfers semiconductor wafers to and from the wafer carrier via an access opening of a housing of the EFEM, and also transfers wafers to and from a semiconductor processing or characterization tool. A gas flow device disposed inside the housing of the EFEM is connected to receive a low humidity gas having relative humidity of 10% or less, and is positioned to flow the received low humidity gas across the access opening. A saturated pressure layer of the gas flow device has a permeability for the low humidity gas that increases with increasing distance from a gas inlet edge of the saturated pressure layer, for example due to holes of varying diameter and/or density passing through the saturated pressure layer. A filter layer of the gas flow device uniformizes the gas exiting the saturated pressure layer.

What is claimed is: 
     
         1 . A gas flow device comprising:
 at least one saturated pressure layer having a gas inlet surface, a gas outlet surface, and holes passing through the saturated pressure layer from the gas inlet surface to the gas outlet surface;   one or more gas nozzles arranged to flow a gas over the gas inlet surface of the saturated pressure layer from a gas inlet edge of the saturated pressure layer;   a gas entry layer disposed at the gas inlet surface of the saturated pressure layer; and   at least one uniform layer disposed at the gas outlet surface of the saturated pressure layer;   wherein at least one of (i) a size of the holes passing through the saturated pressure layer increases with increasing distance from the gas inlet edge of the saturated pressure layer and/or (ii) a density of the holes passing through the saturated pressure layer increases with increasing distance from the gas inlet edge of the saturated pressure layer.   
     
     
         2 . The gas flow device of  claim 1 , wherein the size of the holes passing through the saturated pressure layer increases with increasing distance from the gas inlet edge of the saturated pressure layer. 
     
     
         3 . The gas flow device of  claim 2 , wherein the holes passing through the saturated pressure layer are arranged as mutually parallel straight lines of holes that are also parallel with the gas inlet side of the saturated pressure layer, and the holes of each straight line of holes have increasing hole size with increasing distance of the straight line of holes away from the gas inlet side. 
     
     
         4 . The gas flow device of  claim 1 , wherein the density of the holes passing through the saturated pressure layer increases with increasing distance from the gas inlet edge of the saturated pressure layer. 
     
     
         5 . The gas flow device of  claim 4 , wherein the holes passing through the saturated pressure layer are arranged as mutually parallel straight lines of holes that are also parallel with the gas inlet side of the saturated pressure layer, and the holes of each straight line of holes have increasing hole size with increasing distance of the straight line of holes away from the gas inlet side. 
     
     
         6 . The gas flow device of  claim 4 , wherein the holes passing through the saturated pressure layer are arranged as mutually parallel straight lines of holes that are also parallel with the gas inlet side of the saturated pressure layer, and the holes of each straight line of holes have decreasing hole spacing along the straight line of holes with increasing distance of the straight line of holes away from the gas inlet side. 
     
     
         7 . The gas flow device of  claim 1 , wherein the uniform layer comprises a pleated filter layer. 
     
     
         8 . The gas flow device of  claim 7 , wherein pleats of the pleated filter layer have a height of between 2 mm and 40 mm and a pitch of between 0.1 mm and 2 mm. 
     
     
         9 . The gas flow device of  claim 1  further comprising a diversion layer within which at least a portion of the at least one uniform layer is disposed, the diversion layer having a thickness of at least 3 millimeters. 
     
     
         10 . The gas flow device of  claim 1 , further comprising at least one of at least one O-ring and at least one connect layer disposed at the gas outlet surface of the saturated pressure layer and providing a sealed connection between the gas outlet surface and the at least one uniform layer. 
     
     
         11 . A gas flow device comprising:
 a plenum chamber including:   a saturated pressure layer forming a wall of the plenum chamber, the saturated pressure layer having a gas inlet surface forming an inner surface of the plenum chamber;   a gas outlet surface forming an outer surface of the plenum chamber; and   gas nozzles connecting to flow gas into the plenum chamber at a gas inlet edge of the saturated pressure layer, wherein the saturated pressure layer has gas permeability that increases with increasing distance from the gas inlet edge.   
     
     
         12 . The gas flow device of  claim 11 , wherein the saturated pressure layer has holes passing through the saturated pressure layer from the gas inlet surface to the gas outlet surface, and the gas permeability that increases with increasing distance from the gas inlet edge is provided by a size of the holes passing through the saturated pressure layer that increases with increasing distance from the gas inlet edge of the saturated pressure layer. 
     
     
         13 . The gas flow device of  claim 11 , wherein the saturated pressure layer has holes passing through the saturated pressure layer from the gas inlet surface to the gas outlet surface, and the gas permeability that increases with increasing distance from the gas inlet edge is provided by a density of the holes passing through the saturated pressure layer that increases with increasing distance from the gas inlet edge of the saturated pressure layer. 
     
     
         14 . The gas flow device of  claim 11 , further comprising:
 a filter layer arranged to receive the gas exiting the plenum chamber at the gas outlet surface of the saturated pressure layer.   
     
     
         15 . The gas flow device of  claim 14 , wherein the filter layer comprises pleats. 
     
     
         16 . The gas flow device of  claim 15 , wherein pleats of the filter layer have a height of between 2 mm and 40 mm and a pitch of between 0.1 mm and 2 mm. 
     
     
         17 . The gas flow device of  claim 14 , further comprising:
 a diversion layer within which at least a portion of the filter layer is disposed, the diversion layer having a thickness of at least 3 millimeters.   
     
     
         18 . A gas flow method comprising:
 flowing a gas into a plenum chamber via gas nozzles over a gas inlet surface of a saturated pressure layer from a gas inlet edge of the saturated pressure layer; and   forming a curtain of the gas by flowing the gas from the plenum chamber through holes of the saturated pressure layer, wherein sizes and/or density of the holes increases with distance from the gas inlet edge of the saturated pressure layer.   
     
     
         19 . The gas flow method of  claim 18 , wherein the sizes and/or density of the holes increasing with distance from the gas inlet edge of the saturated pressure layer balances against higher gas flow and/or pressure proximate to the gas inlet edge of the saturated pressure layer to provide a substantially uniform gas flow rate through the saturated pressure layer over a surface area of the saturated pressure layer. 
     
     
         20 . The gas flow method of  claim 18 , wherein the gas has a relative humidity of 10% or less, and the method further comprises:
 flowing the curtain of the gas through a filter layer.